If I was to purchase one of the better head units from ebay (the one with Satnav), would I just simply remove the old one and put the new one in, plus enter in the radio code? Or would I need to program the new one in? Would the ford bluetooth that I currently have running on the car still work? I am coming from using a Vauxhall where head units had to be married and programmed into the hid in the dash.

Any advice would be really good. Not sure if I am definately wanting to, just getting ideas

An upgrade should be a simple case of plug and play assuming that you A. go for a a unit out of the same model car i.e. focus to focus and B. you have the appropriate aerial for the upgrade you intend to do. In the case of the Sat Nav unit you'll need the GPS atennna (which I think is built into the aerial base and mast) This may also require a new loom from the aerial to the head unit. Alternatively an alternative GPS antenna could be placed in an alternative location - inside dash for example.

I changed my Sony single CD for a DAB version - this was a simple swap (as I bought a version from a similar age focus) I did, however have to purchase a new aerial mast, base and 2 part loom to accommodate the DAB connection. Cost £85

Bluetooth should be fine as the information is held in the module.

As said previously, the key to changing the radio is getting a model from the same or similar age model to reduce the chances of incompatibility.

Others have done the upgrade from the 6000 + fitted bluetooth so should be able to comment further.